Because although they cannot see it, they can see it's influence on objects that can be seen, and it's effects.
Answer: set up proportions
Explanation:
Answer: Always ask. ...
Put your weights back. ...
Be mindful of your surroundings. ...
Bring a towel. ...
Clean up after yourself (and, if you have to, other patrons). ...
Selfies: Try to be discreet about them. ...
Personal space: respect it. ...
Don't hog the equipment.
Yes basic, calculus, and trig
because a chemical change takes time
